WO2004063531A1 - Remise sous tension d'un boulon d'ancrage - Google Patents

Remise sous tension d'un boulon d'ancrage Download PDF

Info

Publication number
WO2004063531A1
WO2004063531A1 PCT/AU2004/000021 AU2004000021W WO2004063531A1 WO 2004063531 A1 WO2004063531 A1 WO 2004063531A1 AU 2004000021 W AU2004000021 W AU 2004000021W WO 2004063531 A1 WO2004063531 A1 WO 2004063531A1
Authority
WO
WIPO (PCT)
Prior art keywords
shank
arrangement
support member
hollow shaft
rock
Prior art date
Application number
PCT/AU2004/000021
Other languages
English (en)
Inventor
Jeffrey Robert Fergusson
Original Assignee
Jeffrey Robert Fergusson
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/AU2003/000027 external-priority patent/WO2003058032A1/fr
Priority claimed from PCT/AU2003/000026 external-priority patent/WO2003058033A1/fr
Application filed by Jeffrey Robert Fergusson filed Critical Jeffrey Robert Fergusson
Publication of WO2004063531A1 publication Critical patent/WO2004063531A1/fr

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/008—Anchoring or tensioning means
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
    • E21D21/0033—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts having a jacket or outer tube

Definitions

  • the present invention relates to rock bolts which are used in coal mining, hard rock mining, and civil engineering projects including tunneling.
  • Rock bolts have a leading end and a trailing end with the leading end being inserted into a blind hole drilled in the coal or rock face.
  • One type of rock bolt has only the leading end secured to the interior of the hole (either by resin or grout located at the leading end only, or by an expansion member carried by the leading end and mechanically manipulated to grip the interior of the hole and thereby anchor the leading end of the bolt).
  • Such rock bolts are tensioned after the leading end is anchored, for example, by tightening a nut which is threadably engaged with the trailing end of the rock bolt and which typically bears on an apertured support plate through which the trailing end passes. The support plate in turn bears on the coal or rock face.
  • Such rock bolts are inherently re-tensionable at any time merely by re- tightening the nut.
  • rock bolts may require re-tensioning.
  • the rock or coal face under the support plate is friable or otherwise breaks away. This results in the support plate no longer bearing against the coal or rock and the bolt no longer being in tension. Accordingly, the mechanical support initially provided by the tensioned rock bolt no longer exists in its intended form.
  • rock bolts in order to increase the tensile load able to be carried by the rock bolt and/or to increase the corrosion resistance of the tendon of the rock bolt, most rock bolts have the tendon fully encapsulated in a sleeve of grout or resin. (For yielding rock bolts a portion of the tendon may not be encapsulated in grout or resin but at least the trailing end of the tendon is so encapsulated). Normally this grouting also covers or at least fouls the nut at the trailing end of the bolt thereby making re- tensioning difficult.
  • encapsulated rock bolt has a solid tendon in the form of a hollow shaft.
  • Such bolts are sold under the Registered Trade Mark JUMBOLT owned by the present applicant.
  • This bolt is provided with a castellated ring at its trailing end which is used to rotate the bolt and drive it home during installation.
  • Such bolts have enjoyed widespread commercial acceptance since their commercial release in Australia a few years prior to the priority date of the present invention.
  • the aim of the present invention is to substantially overcome, or at least to some extent ameliorate, the abovementioned problems caused for such hollow shaft rock bolts as a result of the rock or coal face retreating after the bolt has been installed.
  • a re-tensioning arrangement for a rock bolt having a hollow shaft and being adapted to be fixedly secured in a blind hole drilled in a coal or rock face said arrangement comprising a shank having a head and extending through an apertured support member with said head being dimensioned to bear against said support member; said shank and hollow shaft having engagement means whereby said shank can be advanced into said shaft until said support member directly, or indirectly, bears against said coal or rock face to place said hollow shaft in tension.
  • Fig. 1 is a truncated schematic perspective view of a hollow shaft rock bolt having a nut secured to its trailing end
  • Fig. 2 is a perspective view of the trailing end of the bolt of Fig. 1,
  • Fig. 3 is a longitudinal exploded cross-sectional view through a rock bolt with a re-tensioning arrangement in accordance with a first embodiment of the present invention
  • Fig. 4 is a view similar to Fig. 3 but of a modified arrangement to that of Fig. 3,
  • Fig. 5 is a longitudinal exploded cross-sectional view through a rock bolt with a re-tensioning arrangement of a second embodiment
  • Fig. 6 is a view similar to that of Fig. 5 but showing the rock bolt after installation.
  • a rock bolt 117 of the general type of the abovementioned JUMBOLT rock bolts has a shaft 22 which is a hollow cylinder of one of many possible lengths.
  • the shaft 22 is preferably fabricated from conventional steel pipe and preferably has a nominal bore of from 10-30 mm approximately.
  • the shaft 22 has a tip 23 or leading end which is swaged closed so as to create four impellers 24 which are used to shred a resin cartridge (not illustrated) and mix the resin or grout used to hold the shaft 22 of the rib bolt 117 in position.
  • Such a bolt is preferably used in coal mining applications.
  • the bolt is of larger diameter (eg 45- 50mm) for use in hard rock mining applications.
  • a domed washer 25 and an hexagonal nut 26 are secured by a means of a frictional press fit, by welding, by threaded engagement, or by some other conventional such means.
  • the interior of the nut 26 is provided with an internal thread 27 which, was originally intended to be threadably engaged with an external thread 29 on the shank 30 of a support member 31 (Fig. 2).
  • a typical support member 31 is fabricated from a conventional bolt to which is welded a U-shaped link 32. Such support members can be used to support temporary lights, warning signs, etc.
  • the shaft 22 is passed through a support plate 37 which has a recessed collar 38 which mates with the convex face of the domed washer 25.
  • a two-part epoxy resin or grout surrounds the shaft 22 and fills the space between the shaft 22 and the hole (not illustrated).
  • This quick setting resin or grout secures the bolt in position and a hollow tubular spanner (conventional but not illustrated) is used to drive the rock bolt 117 so as to rotate it about its longitudinal axis during the installation procedure.
  • This drives the washer 25 and nut 26 into the recessed collar 38 and ensures that the support plate 37 compresses the coal or rock in the vicinity of the hole. The result is that the coal or rock is stabilized.
  • the shaft 22 is preferably provided with a plurality of keying deformations 28 (only some of which are illustrated) along its length in known fashion (eg. by helically rolling). This ensures good keying between the grout and the shaft 22.
  • the rock bolt 117 instead of being provided with a services support member 31 can instead be utilized with a re-tensioning member 131 as illustrated in Fig. 3.
  • the re-tensioning member 131 takes the form of a threaded shank 129 mounted within a cup 130 having a cylindrical side wall 140.
  • a nut 126 is welded to the cap of the cup 130.
  • the shank 129 and nut 126 can also be formed as a conventional bolt which passes through the cap of the cup 130.
  • Fig. 4 also illustrates a domed washer 125 which is slidably mounted on the bolt 117 rather than being fixed thereto, by welding for example, as illustrated in Figs. 1 and 2.
  • the nut 26 is provided with a radial hole 200 into which a breakable pin 201 is inserted by means of a friction fit.
  • the shank 129 can then have its tip only partially threadably inserted into the nut 26 until the tip of the shank 129 abuts the pin 201.
  • the entire bolt assembly illustrated in Fig. 5 can be mounted in the hole in the rock or coal face 150 but with the conventional driving machinery engaging the nut 126 rather than the nut 26. In this way the support plate 37 is driven against the coal face 150 in the usual way (and without the side wall 140 abutting the support plate 37).
  • the support plate 37 can be brought to again bear against the new face 150 in the following fashion.
  • the nut 126 is rotated thereby causing the shank 129 to rotate relative to the nut 26 which is now fixed by hardened grout.
  • the shank 129 therefore fractures the pin 201 and progresses through the nut 26 until the front edge of the re-tensioning member 131 (in this instance the front edge of the side wall 140) bears against the support plate 37.
  • This re-engagement of the support plate 31 against the face 150 can be repeated several times, if necessary to re-tension the bolt 117 each time.
  • the cup 130 can be replaced with an equivalent cup but with a longer side wall 140, if necessary.
  • a second embodiment of a re-tensionable rock bolt in the form of rock bolt 100 is illustrated.
  • the bolt 100 has a shaft 102 and is essentially as before, however, at the trailing end of the shaft a nut, or a length of internally threaded tube, 106 is welded in place of the nut 26 of the first embodiment.
  • the tube 106 preferably has an outer diameter substantially equal to, or less than, that of the shaft 102.
  • the tube 106 has a hole in one side (similar to hole 200 of Fig. 4) into which a breakable pin 121 is secured by means of a friction fit.
  • An externally threaded drive member 111 having a shank 110 with thread 109 and a chamfered nut 116 is passed through a support plate 17.
  • the shank 110 can then have its tip only partially threadably inserted into the tube 106 until the tip of the shank 110 abuts the pin 121.
  • the entire bolt 100 can be mounted in the hole 140 in the rock or coal face 150 as seen in Fig. 6 but with the conventional driving machinery engaging the nut 116 rather than the tube 106.
  • the tube 106 is driven some distance into the hole 140 during this initial procedure.
  • the support plate 17 is driven against the rock or coal face 150 by the shank 110 breaking the pin 121 and passing through the tube 106.
  • the support plate 17 can be brought to bear against the new face 150 and thereby re-tension the rock bolt 100 in the following fashion.
  • the nut 116 is rotated thereby causing the shank 110 to rotate relative to the tube 106 which is now fixed by hardened grout.
  • the shank 110 therefore progresses through the tube 106 until the front of the support plate 17 again bears against the new face 150.
  • This re-engagement of the support plate 17 against the face 150 can be repeated several times, if necessary.
  • the nut 116 and shank 110 can be replaced with an equivalent nut and shank of different length, if necessary.
  • the keying deformations 28 on the shaft 22 of the bolt 117 of Fig. 1 can form an internal thread on the interior surface of the shaft 22.
  • the re- tensioning arrangement can have a shaft 129 dimensioned to mate with the thread on the interior of the shaft 22. Under these circumstances the cup 130 is dimensioned to pass over the castellated ring and abut the support plate 37.
  • the shank can be provided with a series of frusto-conical protrusions.
  • the nut 26 or tube 106 is provided with a single circular orifice that is slightly smaller in diameter than the maximum diameter of each conical protrusion.
  • the shank can be advanced through the orifice by applying axial blows to the nut 126 or 116 or equivalent, for example by a sledgehammer.
  • the last protrusion to pass through the orifice leaves the plate 37 or 17 compressed against the rock or coal face 150 and the bolt 117 or 100 in tension. If then the face 150 crumbles away, the plate 37 or 17 can be brought back into contact with the new face 150 and the bolt 117 or 100 thereby re- tensioned, merely by applying further axial blows to the nut 126 or 116 or equivalent with the sledgehammer.
  • the cup 130 can take the form of a U-shaped member having two arms 140 which each bear against the support plate 37. Such an arrangement has the same appearance in cross-section as the cup 130 of Figs. 3 and 4.
  • the tip 23 can be crimped onto a threaded rod which carries a substantially conventional expansion anchor. This allows the rock bolt to be initially point anchored. A hole (not illustrated) in the side wall of the tubular shaft 22 near the tip 23 allows for grouting after the initial point anchoring. Thereafter the bolt can be re-tensioned at various time intervals, as needed, in the same manner as the illustrated embodiments.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Piles And Underground Anchors (AREA)

Abstract

L'invention concerne un boulon d'ancrage (100,117) pouvant être remis sous tension après sa première installation. Le boulon d'ancrage comprend une tige creuse (22, 102) recevant, par l'intermédiaire de son extrémité arrière, un corps fileté (109, 129). Le boulon d'ancrage passe à travers un élément support à ouverture (17, 37). Une rotation du corps (109, 129) entraîne l'appui d'un élément de contact (116, 131) contre l'élément support qui, à son tour, s'appuie contre la surface de charbon, de pierre ou d'un autre minéral dans laquelle le boulon d'ancrage est introduit. Le corps fileté (109, 129) peut être logé dans un écrou fileté à l'intérieur (26) ou dans un tube fileté à l'intérieur (106). Le corps (109, 129) peut être fixé temporairement par rapport au boulon d'ancrage au moyen d'une cheville fragile (121, 210).
PCT/AU2004/000021 2003-01-10 2004-01-08 Remise sous tension d'un boulon d'ancrage WO2004063531A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
PCT/AU2003/000027 WO2003058032A1 (fr) 2002-01-11 2003-01-10 Procede et appareil d'exploitation charbonniere par longue taille
AUPCT/AU03/00027 2003-01-10
PCT/AU2003/000026 WO2003058033A1 (fr) 2002-01-11 2003-01-10 Boulon d'ancrage
AUPCT/AU03/00026 2003-01-10

Publications (1)

Publication Number Publication Date
WO2004063531A1 true WO2004063531A1 (fr) 2004-07-29

Family

ID=32714030

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2004/000021 WO2004063531A1 (fr) 2003-01-10 2004-01-08 Remise sous tension d'un boulon d'ancrage

Country Status (1)

Country Link
WO (1) WO2004063531A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105134268A (zh) * 2015-09-16 2015-12-09 孟志强 一种等强锚杆安装结构
CN108374672A (zh) * 2018-02-27 2018-08-07 中国矿业大学 一种加固深部矿井松散煤层巷道围岩的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2131115A (en) * 1982-11-26 1984-06-13 Eastern Co Reinforcing rock structure and nut elements therefor
US5733069A (en) * 1996-11-21 1998-03-31 Schofield, Jr.; John P. Loose roof plate retensioning device
US6637980B2 (en) * 2000-11-25 2003-10-28 Earl Products, Inc. Method and apparatus for re-tensioning a roof bolt in an underground mine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2131115A (en) * 1982-11-26 1984-06-13 Eastern Co Reinforcing rock structure and nut elements therefor
US5733069A (en) * 1996-11-21 1998-03-31 Schofield, Jr.; John P. Loose roof plate retensioning device
US6637980B2 (en) * 2000-11-25 2003-10-28 Earl Products, Inc. Method and apparatus for re-tensioning a roof bolt in an underground mine

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105134268A (zh) * 2015-09-16 2015-12-09 孟志强 一种等强锚杆安装结构
CN108374672A (zh) * 2018-02-27 2018-08-07 中国矿业大学 一种加固深部矿井松散煤层巷道围岩的方法
CN108374672B (zh) * 2018-02-27 2019-04-30 中国矿业大学 一种加固深部矿井松散煤层巷道围岩的方法

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